The Leprechaun is a rare or legendary pet form in the MMO Realm of the Mad God. They will, like all pets, contain 3 abilities that can be leveled up along with the pet, one of which must be heal.
I personally apologize if you did not receive the exact pet skin you wanted (elf and mermaid are the other two currently available).
However I would recommend to you to never buy eggs as a way of getting a good pet because eggs cost an extreme amount of money and tend to not give you a good combination of abilities.
Fun fact: you will spend less money buying food to make a good rare pet all the way from common than you will buying eggs until you get a perfect pet.